Optical emission spectroscopy study of pulsed laser deposition of semiconducting nanoparticles

Abstract

Memory devices that use seminconductor nanocrystals (NC) for charge storage began to receive considerable attention in recent years due to their excellent performance, high capacity of memory and miniaturization. In order to integrate these materials into devices, formation of NCs and oxide layers with controlled stoichiometry, dimensions and homogeneity are required. The optimization of nanoparticle synthesis by laser ablation requires the knowledge of the temporal and spatial scales for nanoparticle formation, and how the nanoparticles are transported and deposited. In this context, plasma optical emission spectroscopy (OES) is a convenient technique to monitor in situ and in real time the evolution of the induced plasma plume composition and species kinetics. In this work, OES is used to determine the composition and energy of the plasma plume species obtained during ablation of seminconductor targets using a KrF excimer ns-laser (=248 nm) . We have characterized the plasma plumes in vacuum, and in the presence of an argon atmosphere at 0.5 and 1 mbar. From registered emission spectra we obtained the electron temperature and density for different distances to the target, and laser fluences. The spatial dependence shows a decrease in electron temperature and density with distance.